In the electronics and computer industry today, cases which hold circuitry that create electromagnetic radiation are shielded to prevent emission of radiation referred to as EMI/RFI. Regulatory bodies set maximum emission levels at various frequencies. Devices failing emission level tests may not be sold. Electronic devices may also need to be shielded from electromagnetic radiation generated by devices outside their cases. In the personal computer (PC) industry, processor speeds are increasing. Electronic devices, such as PCs, must meet strict guidelines in the United States and other countries on the amount of radiation they produce within a given radius. With such high processor speeds, it is getting more and more difficult to ensure that PCs meet the radiation emission guidelines. In addition to the increasing frequency of operation, electronic devices must be manufactured in a cost effective manner to remain profitable.
Personal computers are frequently upgraded in function by users which may require taking apart the computer, adding circuitry, and putting the computer back together. To make this easier for a user to do, most PCs have panels which can be removed, and devices such as disk drives, CD and DVD players inserted into a cage. In some PCs, multiple such devices are staked vertically adjacent to each other. Such devices typically have a gap between them that is a source of EMI/RFI leakage. Additionally, PCs may include an aperture or opening in the case designed for exposing a portion of a single device or component that is positioned in or adjacent to an opening in the case, and a gap may be created between the perimeter of the opening and the outer surface of the device that can also become a source of EMI/RFI leakage. A way of preventing such leakage, while still permitting users to upgrade their systems, is needed.
Complex and costly solutions such as gluing an additional shield to cover gaps are too expensive, add additional parts which make the manufacturing process longer, are expensive, and prevent ease of upgrading by a user. Applying a conductive foam strip with adhesive backing on either the bottom surface of the top device surface, or on the top surface of the bottom device is also difficult for users to perform.
One solution is proposed in copending U.S. patent application Ser. No. 10/126,115, filed Apr. 19, 2002, which is assigned to the same assignee as the present application and the disclosure of which is incorporated by reference herein in its entirety. The Ser. No. 10/126,115 patent application describes situations in which a pair of adjacent devices in a case may create a gap therebetween, and a method and apparatus for closing that gap. However, the solution posed in the copending patent application may also find an application in situations where a single device or component is positioned adjacent to an opening in the case of a PC that may create a potential for EMI/RFI leakage in any gap formed along portions, or the entirety, of the perimeter of the opening in the case.